Master/Slave Decision Device and Master/Slave Decision Method Applied to Network Device

1. A master/slave decision device applied to a first network device, wherein the first network device is coupled to a second network device, and the master/slave decision device comprises: a seed distance detecting unit, for detecting a seed distance between a first seed utilized in a first scrambler of the first network device and a second seed utilized in a second scrambler of the second network device; and a decision unit, coupled to the seed distance detecting unit, for determining the first network device to be a master device or a slave device according to the seed distance; wherein when the decision unit determines the first network device to be the master device, the first network device utilizes a first clock to transmit data; and when the decision unit determines the first network device to be the slave device, the first network device utilizes a second clock to transmit data, where the second clock is different from the first clock; wherein the first clock is a local clock of the first network device, and the second clock is a recovery clock which is generated by performing a timing recovery operation upon a received data by the first network device; and wherein the decision unit determines if resetting the first network device to be the slave device according to a frequency difference between the first clock and the second clock.

2. The master/slave decision device of claim 1 , wherein the first clock is a local clock of the first network device, and the second clock is a recovery clock which is generated by performing a timing recovery operation upon a received data by the first network device, where a frequency of the recovery clock is the same as a frequency of a local clock of the second network device.

3. The master/slave decision device of claim 1 , wherein when the seed distance is between N and (−M), the decision unit determines the first network device to be the slave device, where N and M are positive integers, and N is different from M.

4. The master/slave decision device of claim 1 , wherein when the seed distance is between N and M, or between (−M) and (−K), the decision unit determines the first network device to be the slave device; and when the seed distance is between M and (−K), the first network device re-links to the second network device, where N, M, K are positive integers, N is greater than M, and M is greater than K.

5. The master/slave decision device of claim 1 , wherein when the seed distance is greater than A, the decision unit determines the first network device to be one of the master device and the slave device; when the seed distance is less than B, the decision unit determines the first network device to be another one of the master device and the slave device; and when the seed distance is between A and B, the decision unit does not make a decision, and the first network device re-links to the second network device, where A and B are different integers.

6. The master/slave decision device of claim 5 , wherein after the decision unit determines the first network device to be the master device, the decision unit determines whether the second network device is the slave device; and when the decision unit determines that the second network device is not the slave device, the decision unit resets the first network device to be the slave device.

7. The master/slave decision device of claim 6 , wherein the decision unit gathers variations of the seed distance within a period of time, and determines if resetting the first network device to be the slave device according to the variations of the seed distance.

8. The master/slave decision device of claim 1 , wherein the first network device adopts High-Definition Multimedia Interface (HDMI) standard version 1.4.

9. A master/slave decision method applied to a first network device, wherein the first network device is coupled to a second network device, and the master/slave decision method comprises: detecting a seed distance between a first seed utilized in a first scrambler of the first network device and a second seed utilized in a second scrambler of the second network device; and determining the first network device to be a master device or a slave device according to the seed distance; wherein when it is determined that the first network device is the master device, the first network device utilizes a first clock to transmit data; and when it is determined that the first network device is the slave device, the first network device utilizes a second clock to transmit data, where the second clock is different from the first clock; wherein the first clock is a local clock of the first network device, and the second clock is a recovery clock which is generated by performing a timing recovery operation upon a received data by the first network device, and the step of determining whether the second network device is the slave device comprises: determining if resetting the first network device to be the slave device according to a frequency difference between the first clock and the second clock.

10. The master/slave decision method of claim 9 , wherein the first clock is a local clock of the first network device, and the second clock is a recovery clock which is generated by performing a timing recovery operation upon a received data by the first network device, where a frequency of the recovery clock is the same as a frequency of a local clock of the second network device.

11. The master/slave decision method of claim 9 , wherein the step of determining the first network device to be the master device or the slave device according to the seed distance comprises: when the seed distance is between N and (−M), determining the first network device to be the slave device, where N and M are positive integers, and N is different from M.

12. The master/slave decision method of claim 9 , wherein the step of determining the first network device to be the master device or the slave device according to the seed distance comprises: when the seed distance is between N and M, or between (−M) and (−K), determining the first network device to be the slave device; and when the seed distance is between M and (−K), re-linking the first network device and the second network device, where N, M, K are positive integers, N is greater than M, and M is greater than K.

13. The master/slave decision method of claim 9 , wherein the step of determining the first network device to be the master device or the slave device according to the seed distance comprises: when the seed distance is greater than A, determining the first network device to be one of the master device and the slave device; when the seed distance is less than B, determining the first network device to be another one of the master device and the slave device; and when the seed distance is between A and B, not to determining the first network device to be the master device or the slave device, and re-linking the first network device and the second network device, where A and B are different integers.

14. The master/slave decision method of claim 13 , further comprising: after determining the first network device to be the master device, determining whether the second network device is the slave device; and when it is determined that the second network device is not the slave device, resetting the first network device to be the slave device.

15. The master/slave decision method of claim 14 , wherein the step of determining whether the second network device is the slave device comprises: gathering variations of the seed distance within a period of time, and determining if resetting the first network device to be the slave device according to the variations of the seed distance.

16. The master/slave decision method of claim 9 , wherein the first network device adopts High-Definition Multimedia Interface (HDMI) standard version 1.4.